Minimum side clearance on slicks?

So by these standards we should all be mini tubbing just for what we have now let alone putting a seriously big tire under there?
I think there's many levels of cars and the amounts they are used and the amounts of risk people are willing to take with them. For instance your weekend warrior with four or five maybe six hundred horsepower can probably get away with lower clearances on an every other weekend basis.
On the other hand when you're talking a career racer who races daily with 1600 horsepower or more they are are in danger way more often and are taking way more precautions.
Safety is their number one concerne when they get to pull the trigger on 1600 horses everyday no problem.